With the advancement of information communication technologies, various wireless communication technologies have recently been developed. Among the wireless communication technologies, a wireless local area network (WLAN) is a technology whereby Internet access is possible in a wireless fashion in homes or businesses or in a region providing a specific service by using a portable terminal such as a personal digital assistant (PDA), a laptop computer, a portable multimedia player (PMP), etc.
The IEEE 802.11n is a technical standard relatively recently introduced to overcome a limited data rate which has been considered as a drawback in the WLAN. The IEEE 802.11n is devised to increase network speed and reliability and to extend an operational distance of a wireless network. More specifically, the IEEE 802.11n supports a high throughput (HT), i.e., a data processing rate of up to above 540 Mbps, and is based on a multiple input and multiple output (MIMO) technique which uses multiple antennas in both a transmitter and a receiver to minimize a transmission error and to optimize a data rate.
In a WLAN system, a station (STA) supports a power save mode. The STA enters a doze state to operate so that it is possible to prevent power from being unnecessarily used. When traffic related to data to be transmitted to the STA that is operating in the doze state exists, an access point (AP) may indicate the traffic to the STA. The STA may recognize that the traffic related to the data to be transmitted thereto exists and may request the AP to transmit the traffic. The AP may transmit a frame in response to the request of the STA.
Meanwhile, in a multi channel environment where data is exchanged through a plurality of channels, signaling for channels used for the AP transmitting the frame to the STA may be required. Therefore, an efficient method of transmitting and receiving a frame for the STA that operates in the power save mode in the multi channel environment is required.